Numerous devices have already been proposed for concealing a timepiece display, either in order to protect it, as was the case for pocket watches, or for an aesthetic purpose, for example in order to give wristwatches the appearance of a piece of jewelry, outside the brief moments when one wished to consult the time.
A first type of device is the so-called “reversible” or “reverso” watches, illustrated for example in Patent Nos. CH 161 610, EP 1 189 118 or WO 2004/088436. With all the embodiments disclosed, the mechanism for turning the case over through 180° against the back cover of the case-support is complex. It implements hinged arms, pivots, slide-bars, etc. . . . which make the final product relatively expensive, and even fragile and often difficult to handle.
In order to achieve the same purpose, a second type of device relies on one or two shutters sliding in rectilinear grooves in the case, above the display. Such devices correspond for example to the embodiments disclosed in Patent Nos. CH 331 285, CH 337 138 and EP 1 211 577. These constructions are simpler than the preceding ones, but still have the drawback of limiting the watchcase to a rectangular shape, creating new complications, in particular as regard the horns if the shutters slide along the 6 o'clock-12 o'clock axis. Such devices also have the drawback of becoming increasingly difficult to handle because of the gradual accumulation of dirt in the slideways in which the shutters slide.
A third type of device includes a cover that is mobile in rotation in the plane of the watch to reveal or conceal a subjacent display, illustrated for example by EP Patent No. 0 488 355 including an analogue and digital liquid crystal display (LCD). In the device disclosed a disc, arranged between the back face of the dial and the LCD displays, can be rotated, either to make said displays appear through apertures made in the dial, or, conversely, to conceal them. Since it is not possible to manoeuvre the cover from outside the watch, a relatively complex mechanical drive system is provided.